1. Field of the Invention
The present invention relates to a damper and, more particularly, to such a damper that enables the user to adjust the damping force accurately.
2. Description of the Prior Art
In a regular oil damping device, a piston is moved in a cylinder to squeeze a fluid (oil) out of an oil hole or valve. The fluid buffers the moving speed of the piston. This structure of oil damping device cannot eliminate oil leakage after a long sue. FIG. 1 shows a damper that eliminates the use of a fluid. This structure of damper comprises a cylinder 12, the cylinder 12 having a cylinder chamber 12c, , and two end holes 12d in two end walls thereof, a stop rod 16 axially slidably inserted through the end holes 12d of the cylinder 12, the stop rod having an outer thread 16c, a nut 14 disposed inside the cylinder 12 and threaded onto the outer thread 16c of the stop rod 16, a steel ball 182, a compression spring 181 mounted in a side hole of the cylinder 18 and pressed on the steel ball 182 against the nut 14, and an adjustment screw 18 threaded into the side hole of the cylinder 18 and stopped at the compression spring 181 against the steel ball 182. This structure of damper is not easy to assemble. Further, because the friction force between the nut 14 and the stop rod 16 is high, the user cannot accurately adjust the damping force of this structure of damper.
The present invention has been accomplished under the circumstances in view. It is one object of the present invention to provide a damper, which enables the user to adjust the damping force accurately. It is another object of the present invention to provide a damper, which is easy to assemble. It is still another object of the present invention to provide a damper, which can be used as a positioning structure. According to one aspect of the present invention, the damper comprises a barrel axially slidably mounted on a shaft, an elastic ring mounted inside the barrel around the shaft, arched pressure blocks mounted abutted against one another inside the elastic ring around the shaft, each arched pressure block having an axially extended sloping groove, steel balls respectively arranged in the sloping groove of each arched pressure block in contact with the periphery of the shaft, a rigid locating ring mounted inside the barrel to support the steel balls in the sloping groove of each arched pressure block, a screw cap threaded into one side of the barrel, a compression spring stopped between the screw cap and the locating ring, a hollow adjustment screw member threaded into one side of the barrel to support the steel balls in the sloping groove of each arched pressure block against the locating ring. According to another aspect of the present invention, a return spring is provided between the shaft and the adjustment screw member for quick return of the barrel.